<!DOCTYPE HTML>
<html lang="en-US">
<head>
	<meta charset="UTF-8">
	<title></title>
	<style type="text/css">
	*{margin:0;padding:0;font-size:12px;}
	ul{list-style:none;list-style-position:outside;}
	.demo{width:400px;margin:20px auto;}
	.demo li{float:left;width:50%;line-height:50px;text-align:center;margin:-1px;position:relative;border:1px solid black;background:white;}
	</style>
</head>
<body>
	<div class="demo">
		<ul>
			<li>1</li>
			<li>2</li>
			<li>3</li>
			<li>4</li>
		</ul>
	</div>
</body>
</html>